The study, which analyzed blood-alcohol levels in 58,000 suicide cases, found 24 percent of men and 17 percent of women had blood-alcohol levels that met the standard legal definition of intoxication, a level of at least 0.08 g/dL. The rates were higher among young men, American Indians/Alaska Natives, veterans and those from rural areas or with lower education levels. Use of a firearm, hanging or falling as suicide methods were also associated with higher intoxication rates.

“Suicide is a major health problem, and alcohol plays a major role in many of those suicides,” Kaplan said. “In order to reduce the level of suicide, we will have to address the problem of acute alcohol use.”

Suicide is the 10th leading cause of death in the United States, accounting for nearly 37,000 deaths each year. Most academic studies on the link between suicide and alcohol have centered on chronic long-term use, including alcohol dependence. This study is the first to analyze male and female suicide victims aged 18 or older in 16 states from 2003-2009 in the National Violent Death Reporting System who were legally intoxicated at the time of death.

Researchers found the levels were almost twice as high for American Indian and Alaska Native groups: 41 percent for men and 33 percent for women. Men who used guns to kill themselves were 76 percent more likely to be drunk, and men without high school diplomas were 41 percent more likely to be drunk at the time they died.

“Intoxication or high-volume drinking may reduce the inhibitions that protect against suicide and thereby become an immediate risk factor for self-harm,” Kaplan said.

The study is part of an ongoing collaboration of PSU, Oregon Health & Science University and several institutions throughout the United States and Canada. Kaplan, the lead investigator, has been researching suicide for 19 years, most recently on suicides among returning military veterans.

The 16 states included in the study are Alaska, Colorado, Georgia, Kentucky, Maryland, Massachusetts, New Jersey, New Mexico, North Carolina, Oklahoma, Oregon, South Carolina, Rhode Island, Utah, Virginia and Wisconsin.

The next steps of the research will be to look closer at race and ethnicity and to try to understand the underlying factors of acute alcohol use and suicide, including violent suicide methods and the geographic density of stores that sell alcohol. Results could lead to targeted prevention strategies designed for population subgroups identified at high risk of alcohol-associated suicide.

The research was funded with a grant from the National Institute on Alcohol Abuse and Alcoholism, a branch of the National Institutes of Health.